WO2010007455A2

WO2010007455A2 - Equipment for controllable fine milling of tires and other elastic materials with ultra-high pressure liquid jet process

Info

Publication number: WO2010007455A2
Application number: PCT/HU2009/000061
Authority: WO
Inventors: György MOLDOVAN
Original assignee: Moldovan Gyoergy
Priority date: 2008-07-17
Filing date: 2009-07-17
Publication date: 2010-01-21
Also published as: HUP0800444A2; HU0800444D0; WO2010007455A3

Abstract

Equipment for controllable fine milling of tires (31) and other elastic materials by ultrahigh pressure liquid jet process, to the main feature of the equipment that milling is performed by a group of high-speed linear- vibrating liquid jets that are perpendicular to the forward motion of the workpiece in such way that jets are perpendicular also to the surface of the workpiece or slightly inclined to that perpendicular; and the speed of vibration considerably exceeds the speed of forward motion of the workpiece. For the sake of dynamic balancing of milling system the linear vibrating motion is performed by twindriven milling heads (40, 140, 240), which solution also enables processing of workpieces in pair. Fineness of rubber-grain product is principally controlled by coordinated motion parameters of milling, namely by forward speed of workpiece and the frequency of vibration.

Description

Equipment for controllable fine milling of tires and other elastic materials with ultra-high pressure liquid jet process

Subject of present invention is such equipment that is suitable for continuous production of homogenous fine-grain rubber product in economic quantity among permanent industrial conditions, primarily from used tires by applying ultra-high pressure liquid jet ing technology, and its product is applicable for direct in-material re-utilization.

Background of invention

A considerable limitation of in-material recycling, namely re-utilization in new rubber products of used tires and other rubber industry wastes - that mean increasing environmental burden — is the very limited applicability of the product manufactured by conventional mechanical grinding processes. A common characteristic of both ambient-milled and cryogenic products is the remarkably limited chemical reactivity. The limited purity of products - mostly in case of tires - means further problem as the mechanical grinding processes mill the tires completely and the particles of reinforcing metal and fibre cords are separated from the product subsequently. Production cost of high-purity fine products is consequently high particularly if further chemical or physical attempts are being ap- plied for increasing the chemical activity of products.

Most part of these problems can be prevented with ultra-high pressure liquid jet milling of tires as well as other rubber industry wastes or rejects. The jet — that is primarily high- purity water for practical reasons - would strip the elastic parts only, leaving the reinforcing metal framework intact. Due to this reason there is no metal contamination in the milled product. Selectivity is a further advantage of this process. By controlling the milling parameters of the jet and by proper construction of milling equipment, a separated milling of different outside and inside rubber layers of the tire can be achieved. As a result of this process the different rubber qualities of tire are not mixed up, in contrary to the products of the conventional mechanical milling processes. Achievement of these attractive targets generates wide-range continuous efforts worldwide, and the result is that proposals for solutions are also very comprehensive. Different process trends can be well separated in respect of introduced technological suggestions. Processing of whole tires are proposed by e.g. Rutherford in US 5,115,983 and Jacca- choury in FR 2773727 on a conveyor system, as well as Rutherford in US 5,341,996 by processing in an individual unit and Shinal in US 5,683,038 by combination of different processes.

Processing of tires by separation of carcass is proposed among others by Loic in FR 2798089 and Lambert in FR 2798090, Veres in US 5,482,215, Begler et.al in DE 198 18 566 and Baliko et.al in WOO 1/53053.

It can be summarized that most part of the comprehensive proposals provides general description of technology and equipment, but the proposals would not supply appropriate education for realization of equipment that fulfils the targets under economic construction and operation conditions.

Aim of the invention

The aim of the invention is to present an appropriate education for construction of equipment for production of homogenous fine- grain rubber product among permanent industrial conditions continuously producing in economic quantity, while the equipment is being economically reproducible, and offers reliable and cost-effective operation

Recognition of invention basis

The apparatus of present invention is primarily suitable for processing of truck tires of steel-cord carcass but also for other elastic materials of different appearance (wastes of rubber industry and production rejects). As its theory of tire processing it realizes the technology by separation of tire body. Basis of this approach is that one of the most im- portant conditions of ultra-high pressure jet milling of elastic materials is to fix the work- piece properly and to support it firmly on its base opposite to impact of jet. In case of having no firm support the flexible workpiece behaves like a mechanical compensator that would cause considerable loss of milling energy in the workpiece without effective milling result.

If we tried to mill the tire in its whole form, the industrial realization of firm support of every tire part at actual milling place would be quite difficult and costly. Accordingly, the main steps of our milling technology are the followings. 1) Milling the tread part of tire 2) Milling the outside and inside part of separated sidewall (or side-disc)

(Separation of sidewall of tire is performed by a mechanical cutter, which is not subject of present invention)

3) Milling the internal part of tread-ring (The tread-ring is being cut up into tread-band by a mechanical apparatus, which is not subject of present invention)

The fineness of product can be basically controlled by motion parameters of the milling: slower forward speed of workpiece results finer grains, but the same result can be achieved by higher jet- vibrating frequency under the same workpiece (or jet) forward speed. Taking into consideration that frequency of vibration has a practical construction upper limit, the milling parameters and consequently the size of rubber grains can also be optimized by joint controlling of correlative motions of the forward speed and the vibration frequency.

These steps known from the industry are realized by this invention with a fundamental difference that the milling jets would reach the most effective milling conditions defi- nitely by a linear (or planar) movement instead of different circular or similar spatial trajectories described in various literatures.

Essence of invention and further advantageous characters Essence of the milling technology of invented apparatus is that perpendicularly to the forward movement of the workpiece several grouped jets perform a linear/planar vibrating motion, where the speed of this motion considerably exceeds the forward speed. It is a further convenient solution that the milling head incorporating jet nozzles performs its vibrating motion in the vicinity of the surface of workpiece, in parallel to the surface of workpiece (or actual tangent of the surface). By minimizing the free-flow distance of the milling jet it can be guarantee that milling would be realized with the least energy loss. It is a further important characteristic that adjustment of the center of tire to be milled to different tire diameters, as well as readjustment of this center during milling process is arranged by telescopic tubular driving shafts, thus ensuring the minimum distance between surface of the tire and the milling head; and for additional minimizing of free-flow length of milling jet between discharge rim of the nozzle and the surface of workpiece we apply front-orifice nozzles in milling heads. It is a further important characteristic that for the purpose of optimization of milling process we arrange the readjustment of above-mentioned driving shafts during milling by an automatic control system.

It is an important characteristic of the invention that the dynamic balancing of kinetic system of the milling head vibrating in the range of 250/min to 1550/min — which is nec- essary for the optimum grain-size distribution - is performed by twin-arranged counter- motion of the milling heads.

It is an important characteristic of the invention that by the twin- arrangement of milling heads the workpieces can also be processed in twinned arrangement. By this symmetric arrangement of the equipment the workpieces can be doubled or multiplied on both sides of the equipment.

It is a further important characteristic that the processing capacity of the equipment can be further increased by multiplied milling heads.

It is a further important characteristic that the milling jets are inclined to some degree (0- 5°) to the perpendicular to the surface of workpiece in the direction of forward motion of workpiece, thus promoting the milling effectiveness by pre-stressing the workpiece. Inclination of milling jets can be adjusted by inclination of milling heads in such way that milling heads are fixed on vibrating shafts by releasable clamped fastening. It is a further advantageous characteristic of the invention that for the optimization of milling process the milling head is assembled from contour-following milling blocks according to the contour of surface to be milled.

It is a further advantageous characteristic that the tire for tread milling shall be fixed on its driving shaft by a supporting-clamping hub that also makes the quick and safe assembly and replacement of workpiece possible. It is an important characteristic of invention that back-up of tire sidewall during its milling is maintained by a supporting die that corresponds to the counter-shape of the opposite side of the sidewall, and centring of workpiece is maintained by upright wing-pieces that Fit to the actual position of bead rim of the sidewall. It is a further important character that the on-site fastening of the sidewall in the milling area is made by a pneumatic- driven roll-type hold-down unit.

It is an important characteristic of the invention that the milling of internal rubber layer of the tread-band is performed on belt-type milling equipment, where supporting of workpiece is made by plane plate-surfaces and its forwarding is arranged by synchronized roll- pairs. Supporting at the milling place is made by a fixed spacer arranged between a pair of auxiliary rolls.

It is a further important characteristic that transfer of feeding force at driving rolls is controlled by pushing force perpendicular to the surface of workpiece, and the surface of pull-side rolls is covered with a material of increased friction property. It is an important characteristic of the invention that for the sake of operation-safe feed- ing of ultra-high pressure liquid to the high-speed vibrating milling head the applied flexible feed line (hose) is arranged by shaping a compensation curve for vibration- damping, and the connections of the hose are made with anti-vibration connectors that allow a minimum +/-1° but not more than +/- 2,5° inclination of the feeding hose. It is a further advantageous characteristic that the homogenous grain dispergation in product-collecting and slurry tank is maintained by a slurry mixer driven from outside of tank.

It is a further advantageous characteristic that for the promotion of slurry discharging from collecting tank the bottom of tank shall be inclined by 3-5° in such way that prevents the product sedimentation. Magnetic separators are also applied with bottom settling spaces between spillways.

It is a further advantageous solution that for the promotion of condensing the steam phase produced during milling process and for the sake of gravitation drainage of the liquid an inclined shaping of the top and the side walls of the equipment is arranged, including the doors of equipment, as well.

It is a further advantageous characteristic that doors of the equipment have vapour-tight sealing, which sealing also provides vibration-damping and noise-insulating function. It is an important characteristic of the invention that mechanical components that would pollute the product or the milling liquid may not be applied inside the milling compartment (e.g. hydraulic cylinder). Also for the sake of preventing occasional pollution the rotating or moving components, driving shafts etc. can be led into milling section via multiple labyrinth-packing

Brief description of drawings

The invention will be interpreted in details on basis of drawings, where Figure 1 Construction of tire tread milling machine Figure 2 Shaping of milling machine bonnet

Figure 3/a-b Side-views of slurry-collecting tank of milling machine Figure 3/c Axonometric view of slurry-collecting tank of milling machine Figure 4/a Tire-clamping hub in mounting status Figure 4/b Tire-clamping hub in fixed (supporting) status Figure 5 Tire-turning drive with supporting slide mechanism Figure 6 Twin driving of milling heads Figure 7 Arrangement of milling blocks into milling heads

Figure 8/a-b Milling block with front-orifice nozzles

Figure 9/a Undamped flexible feed line

Figure 9/b Flexible feed line damped with compensation curve Figure 10 S idewall-milling equipment

Figure 11 Supporting die for outside milling of sidewall

Figure 12 Roll-type hold-down unit

Figure 13 Milling area of sidewall

Figure 14 Schematic arrangement of tread-band milling

Detailed explanation of machine construction

Equipment for milling of tire tread

Structure of tire tread milling machine can be seen on Figure 1, where the subsequent detailed construction points can be directly followed. For the sake of easier understanding of construction the equipment is represented without bonnet and auxiliary components.

Considerations in structuring of equipment body

10 frame shall provide self-supporting of machine construction and supporting of 30 tire- clamping hub with 31 tires of considerable mass. The frame shall be solid also for damp- ing the secondary vibrations resulting from the high-speed vibration of 40 milling head system. Equipment shall also be suitable for realization of precise correlative movements of the workpiece and the milling jet.

Geometric shaping of 11 bonnet shown on Figure 2 and workpiece loading-unloading 12 and 13 doors promotes the drainage of splashing liquid and condensing vapour on inter- nal surface of bonnet wall. Considerable quantity of vapour originates from impact energy of high-speed milling jet. For the promotion of condensing the steam phase produced during milling process and for the sake of most active drainage of the liquid it is practical to provide an inclined shaping of the top and the side walls of the equipment, as shown on the figure. At the same time it is also practical to arrange a vapour-tight sealing of machine doors, thus considerably decreasing the evaporation liquid loss. The sealing of doors is also provides a vibration-damping and noise-insulating function. Discharging of rubber-liquid mixture is made from 60 slurry-collecting tank, shown in details on Figure 3/a-c. It is advised to keep up homogenous mixture-phase in the slurry- collecting tank for the sake of preventing the product sedimentation and blocking of discharging pump, as well as mixing in the fine rubber particles that otherwise tend to float on surface of the slurry. Uniform product-dispergation in the slurry can be arranged by a slurry mixer driven from outside of tank. Driving of mixer from outside is necessary for the sake of preventing such mechanical components inside the milling space and slurry tank that, in any way e.g. with residues of lubricant may pollute the clean liquid-rubber mixture. If an internal mechanical component cannot be avoided, appropriate labyrinth-packing shall be applied at the passage. For the promotion of slurry discharging from slurry-tank, the 61 bottom of tank shall be inclined in such way that prevents the product sedimentation. Its practical value is 3-5°. From milling practice it may be observed that together with rubber grains steel-cord filaments also appear in the slurry despite of the fact that the liquid without abrasives would mill the elastic parts only. The reason of appearance of steel-cord filaments is that the steel-cord carcass has been corroded or the tire was overrun and the steel-cord is beyond its original material fatigue limit. By milling of rubber from the steel-cord layer, the Hb- erated cord-filaments may peel off. The steel filaments being heavier than rubber particles can be separated by settling spaces between 62 spillways. Separation effect may be increased also by magnetic spillways.

For the sake of easier cleaning of slurry-tank, its longitudinal bottom-line may get a bevelled joint, thus decreasing the product sedimentation in the corners. The bevelled bot- tom-line also promotes the homogenous product dispergation generated by slurry mixer. The bottom-line arrangement can be seen also on Figure 3/c axonometric view of slurry- collecting tank.

Considerations of clamping and motion of tire Tire-clamping hub As it was discussed before, one of the most important conditions of milling of elastic shapes by ultra-high pressure liquid jet is the proper fixing of workpiece and the firm supporting on the opposite to impact of jet. These conditions are realized by the tire- clamping hub shown on Figure 4/a in mounting status and on Figure 4/b in fixed (sup- porting) status. Firm supporting of the tread of 31 tire is maintained by 32 supporting segments that follow the internal contour of the tread. Between 32 supporting segments and 33 centring disc there are 34 supporting rods that move interlocked with the 35 hinge assembly that maintains concentric spanning and 37 spanning capstan that moves on 36 external-threaded hub. In the mounting position shown on Figure 4/a the 37 spanning capstan and the interlocked 35 hinge assembly are in top draw-in position. At this status the 32 supporting segments and 34 supporting rods can be inserted by elements. Mounting ability of 34 supporting rods is maintained by forked ends of the rods that are positioned to the direction of 33 centring disc so they can be snapped in axle-stubs of 35 hinge assemblies in 33 centring disc.

For the fixed (supporting) status shown on Figure 4/b the 37 capstan shall be driven down, so spanning the 32 supporting segments by the 34 supporting rods, thus maintaining the firm support of tire tread for milling.

Driving system of tire

Figure 1 functionally shows the 20 tire rotating driving system, which has a substantial aspect in structure: the driving is arranged from outside the milling compartment for the reason that lubrication materials of mechanical components of driving system (e.g. reducing gears) may definitely not pollute the clean product. Size-adjustment of tires of differ- ent diameters is arranged by a driving shaft assembly shown by Figure 5 in details. This mechanism makes it also possible to minimize the distance between milling head and the surface of workpiece. Actual position of tire supporting shafts can be controlled by adjusting the length of telescopic tubular driving shaft-assembly consisted of 21 driving tubular shaft and 22 driven shaft. Minimizing of free-flow of milling jet by length-adjustment of driving shaft can be maintained easier than adjustment of position of high-speed vibrating milling head. Free-flow minimizing of jet by adjustment of milling head would require the movement of complete driving mechanism and feeding system of ultra-high pressure liquid. That arrangement would be technically more complex task with uncertain results in respect of stable operation safety.

Minimizing of jet free-flow distance can be arranged manually by periodic or occasional suspension of milling process, then by inspection of actual distance between the work- piece and milling head and by necessary adjustment. Nevertheless the measuring- controlling process can be also automated, thus operational effectiveness and optimization of the milling process can be successfully controlled.

According to the results of milling practice the forward speed of tires and other work- pieces is optimum between 0.002 m/s and 0.02 m/s. For the sake of controlling the variable speed can be arranged by stepless drive, e.g. by frequency converter driven electric motor.

Driving of milling heads

According to practical experience the vibration speed of milling heads that necessary for the optimum grain-size distribution is between 250/min and 1550/min depending on physical characteristics of workpiece. Speed of vibration can be adjusted by stepless regulation, also by frequency converter driven electric motor as most practical solution. Further to driving of vibrating system its dynamic balancing is also substantial in respect of its long-term operation, mainly in higher frequency ranges. The dynamic balancing of kinetic system, consisting of the mass of milling heads, the considerable kinetic energy of milling jets and mechanical components of feeding milling liquid represent such dynamic mass that simply by applying counter-balance will not give acceptable solution in operation respect.

Dynamic balancing can be solved practically by twin- arrangement and counter-motion of milling heads according to functionally shown 50 milling head driving on Figure 1. The actual arrangement can be seen on Figure 6. As the most practical mechanical solution the crank drive system could be found, although theoretically the cardioid-contour trajectory motion is more advantageous in respect of stroke-end position acceleration- deceleration of milling-head masses. Nevertheless the crank drive system can be consid- ered more reliable for the sake of permanent operational conditions, as it was also confirmed in our practice.

Obviously, the vibration of 40 milling-head system can be achieved also by different methods instead of discussed mechanical driving, such as electromagnetic, pneumatic, hydraulic, spring- force storage etc. driving or combination of these solutions. Actual state of the art however offers the frequency-converter electromotor-driven mechanical crank drive as the most simple, yet long-term reliable solution.

It should be mentioned that milling process is advantageously affected by a certain inclination of direction of milling jets, namely if they are inclined some degrees (0-5 degrees) to the normal (perpendicular) of the surface of workpiece in the direction of its forward motion. As a result of inclination the tangential component of milling force vector (parallel to surface of workpiece) promotes the milling effectiveness by pre-stressing the work- piece.

Inclination of milling jets can be easily adjusted by inclination of milling heads according to Figure 6, as 40 milling heads consisting of 41 milling blocks are fixed on vibrating shafts by releasable clamped fastening.

Construction of milling heads

In the respect of industrial and efficient production it is advantageous if milling of workpiece is performed by several parallel jets. The number of line-nozzles is determined - among other factors - by width of the surface to be milled. From the aspect of optimization of milling process it is also advantageous if line-nozzles closely follow the contour of the surface to be milled. The arch-contour of toroid-like surface of a tire can be properly followed by arrangement of milling blocks according to Figure 7 shown by an axonometric view. Distribution of milling liquid is also shown on the figure by 42 dis- tributor of milling head (feeding the milling blocks) and 43 central distributor of the equipment that feeds the milling heads.

By the construction of milling blocks it is also important to maintain the shortest possible free-flow distance between nozzle orifices and the surface of workpiece. It may be ar- ranged by application of so-called front-orifice nozzles in milling heads. It is characteristic for these nozzles that the sapphire orifice that determines the discharging diameter and beginning of free-flow zone of jet is built in the nozzle near to ejection rim of the nozzle body. According to our milling practice this is an important arrangement in minimizing the free-flow distance of jet between discharging point and surface of the workpiece. Dif- ferent views of a milling block equipped with front orifice nozzles shown on Figure 8/a- b.

Feeding of liquid to milling heads

Feeding of liquid to milling heads is a special task in the respect that a considerable quantity of ultra-high pressure liquid should be transferred to high-speed milling heads vibrat- ing in the range of 250/min to 1550/min. The ultra-high pressure flexible hoses and their connectors being available in technical practice are designed for transferring of liquid under basically static or occasional slow motion of the hose, thus they are not directly suitable for continuing cyclic fatigue stresses caused by periodicity of the vibration. If the 45 flexible feed-hose were guided between static point of 43 central liquid distribu- tor and the high-speed vibrating 42 milling head as per evident shortest way, the vibrating motion would be perpendicular to the direction of fixed connection. In this case the fatigue stress of feed-hose and its fittings is maximum and practically undamped, so the hose and its fittings would be permanently damaged in a short time — even after some hours of continuous operation. For the sake of reduction of fatigue stress the trajectory of 46 flexible hose is arranged along a compensation curve turning back by 180°, according to Figure 9/b. It can be reached by this way that direction of fixed feeding will correspond to the direction of vibration and by application of compensation curve the travelling and standing waves formed by vibration shall be considerably damped. This arrangement can considerably increase the life-span of 46 flexible feed-lines up to several hundred operation hours. Danger of cracking and fracture in connecting fittings of feed-hose can be further decreased that instead of rigid connectors so-called anti-vibration connections are to be ap- plied, that allow minimum +/-1° but not more than +/- 2,5° inclination of the feeding hose.

Capacity-increase of the equipment

By twin-type arrangement of milling heads there is a possibility for simultaneous milling of two tires, as shown on Figure 1. Driving of the tires is made by 20 double-shaft twin driving, where driving of the shafts is arranged by distributed forced direction (e.g. chain or belt driving etc.).

Production capacity of equipment can be further increased by milling of two or more tires on both sides or by doubled or multiplied milling heads, or by combination of such solu- tions, namely by multiplied tire milling with multiplied milling heads.

Equipment for milling of sidewalls of tires

Principal construction considerations of the equipment, such as 110 machine body and 120 bonnet shown on Figure 10, correspond in several respects to the tread-milling equipment previously discussed, therefore we consider those arrangements valid also for sidewall milling equipment. As it can be seen on figure, determining machine components like 150 milling head drive and 160 slurry tank are also identical to previous solutions. Different characteristics of this equipment shall be discussed as follows. A basic difference results from specialities of shape of workpiece. Instead of milling of the former toroid-like shape the actual task is the milling of a special disc-like workpiece. For this reason the 130 supporting and fixing of workpiece as well as the adjustment of 140 milling-head assembly are substantially different.

Supporting of sidewall shall be made according to Figure 11, where 131 sidewall disc, to be milled at its outside surface, rests on the 132 supporting die that is shaped to the inter- nal contour of sidewall. Centring of workpiece is arranged by 133 low-level upright wings. As the supporting die introduced on figure is prepared for the milling of outside of sidewall, its contour obviously corresponds to internal shape of sidewall. Clamping of the workpiece in the vicinity of actual milling area is arranged by 134 roll- type hold-down unit, shown on Figure 12. The hold-down unit shall maintain fixing of flexible part of sidewall, thus its safe milling. Since this unit is within the milling compartment, hydraulic clamping may not be allowed. For this reason the moving and pressing of rolls can be arranged by pneumatic, electro-mechanical or other solution that has no pollution effect. Figure 13 shows the milling area of sidewall, where 136 supporting die, this time prepared for milling of internal part of 135 sidewall (where the contour of die follows the outside contour of the sidewall disc) and the 137 high-level upright centring wings together with the arrangement of 140 milling head and 134 roll-type hold-down unit.

Equipment for milling of internal rubber layer of tread-band of tire

After milling the sidewalls the only remaining part of tire appears in ring-form with outside surface of steel-cord carcass consisting of several cord layers, while its internal side is generally air-tight (butyl) rubber layer. By cutting up this ring the tread appears in belt form. Basic construction considerations of this tread-band milling equipment also correspond in several respects to the milling machines previously discussed, therefore we consider those arrangements valid also for the case of present milling equipment. Only different characteristics of this equipment shall be discussed as follows. Main difference is the forward-driving of workpiece. Due to belt-type appearance the driving between roll-pairs is suitable. Figure 14 shows that supporting of 201 workpiece before and after the milling area can be arranged by 202 and 203 plane surfaces, at milling area by 204 and 205 supporting rolls and by a fixed spacer arranged between the supporting rolls. 202 and 203 plates can be perforated for the sake of decreasing the friction and for the advantageous collection of milled product. Construction aspects of workpiece-feeding mechanism are the followings. After extraction of butyl rubber the steel-cord carcass of tread-band is kept together just by the bonding rubber layers between the steel-cord layers. Therefore the forward motion should be arranged rather by pushing than by pulling force. This arrangement is main- tained by controlling the turning speed and force-regulation of 207 and 208 feeding rolls, then the 204 and 205 supporting rolls and finally the 209 and 210 pulling rolls. Transfer of the forces for feeding and pulling motion needs at least two rolls at each sections for the sake of safe operation in such way that the feeding and pulling rolls in the milling vicinity shall hand over and take over the workpiece in the shortest possible dis- tance at the 204 and 205 supporting rolls.

Role of the pulling rolls after milling is mainly to maintain the speed of workpiece that corresponds to the forwarding speed. At the construction of pulling rolls it should be taken into consideration that the friction of steel-layer without butyl cover shall not be enough for the reliable transferring of the pulling force, therefore the surface of 209 and 210 pulling rolls must be covered with an increased friction layer, practically with some kind of abrasion-resistant elastomer.

Transfer of driving force to the 207, 208, 209 and 210 rolls can be controlled by a pushing power perpendicular to the surface of workpiece. With due consideration of the basic rule that hydraulic cylinder may not be applied in the milling compartment, the force- control is practically arranged by pneumatic drive.

The describer equipment can be applied in every case where the workpiece is belt-like or it can be formed to such shape. The equipment can be utilized well for milling of used or factory-reject conveyor belts or different elastic wastes or rejects of similar shape. Another advantageous application field of the equipment is milling of such technical rub- ber workpieces where metal reinforcing structure would not allow the conventional mechanical milling. Such workpieces placed in lined arrangement on a perforated tray and fixed by individual fastening or in group by a covering metal mesh can be fed to milling machine. Forwarding mechanism of workpiece trays shall be modified according to the applied trays. Advantages related to the invention

Equipment to be built according to interpreted machine constructing principles will be suitable for continuous production of homogenous fine-grain rubber product in controlla- ble sizes and in economic quantity under permanent industrial conditions. By way of permanent operation ability the production in industrial quantity can be realized. The introduced equipment are constructed from such machine components that are interchangeable among the machine-types, available in everyday industrial trade or can be easily reproduced by manufacturing. These features are advantageous from aspects of operation reliability and the maintenance, as well.

Main advantage of the invention is that without preliminary shredding and just by application of the interpreted equipment the recovery of rubber material of used tires can be completely solved in the form of high quality pure rubber product. The steel-cord material shall not be milled in the technology therefore it does not pollute the product and it also can be well utilized. Occasional non-steel cord-materials can be efficiently cleaned out from the rubber by well-known separation equipment. It is a further advantage of the invention that by its application the milling of such very soft technical elastomers like silicone rubber or EPDM becomes also possible. Processing of these soft elastomers is either impossible or very difficult by conventional ambient mechanical milling methods. It is also advantageous that the equipment of invented jet-milling principle is also suitable for processing of such technical rubber components that cannot be processed by conventional grinding methods due to their strong reinforcing metal-structure. It is further advantageous that on the tread-band milling equipment other belt-like work- pieces, like used conveyor belts or production wastes/rejects, or other objects that can be transformed into belt-like appearance can be processed and furthermore this equipment can be altered also for extracting the rubber layer of in-line arranged individual work- pieces.

Claims

1) Equipment for controllable fine milling of tires(31) and other elastic materials by 5 ultra-high pressure liquid jet characterized in that perpendicularly to the forward movement of the workpiece several grouped liquid jets perform a linear vibrating motion that motion considerably exceeds the forward speed; and the milling head (40, 140, 240) incorporating jet nozzles is arranged in the vicinity of the surface of workpiece and it is moved in parallel with the surface or the actual tangent of surface of the workpiece.

10

2) An equipment as claimed in claim 1, characterized in that adjustment of the center of tire (31) to be milled to different tire diameters, as well as readjustment of this center during milling process is arranged by telescopic tubular driving shafts.

153) An equipment as claimed in claim 2, characterized in that for the purpose of optimization of milling process the readjustment of tire-driving shafts during milling is performed by an automatic control system.

4) An equipment as claimed in any of previous claims, characterized in that milling 20 heads (40, 140, 240) incorporate front-orifice nozzles.

5) An equipment as claimed in any of previous claims, characterized in that for dynamic balancing of kinetic system of milling heads (40, 140, 240) the milling heads are positioned in twin arrangement and perform counter-motion to each other

25

6) An equipment as claimed in claim 4, characterized in that workpieces are also positioned in twin arrangement. 7) An equipment as claimed in claim 5, characterized in that workpieces on both sides of twinned milling are in a doubled or multiplied arrangement and/or the milling heads (40, 140, 240) are in a multiplied arrangement.

58) An equipment as claimed in any of previous claims, characterized in that the milling jets are inclined to some degree to the perpendicular to the surface of workpiece in the direction of forward motion of workpiece, and the milling heads (40, 140, 240) are fixed on vibrating shafts by releasable clamped fastening.

lθ9) An equipment as claimed in any of previous claims, characterized in that the milling heads (40, 140, 240) are assembled from milling blocks that are arranged in a position to follow the contour of surface to be milled.

10) An equipment as claimed in any of previous claims, characterized in that the tire 15 to be milled on its tread (31) is fixed on tire-driving shaft by a supporting-clamping hub that is equipped with supporting segments (32) that follow the internal contour of the tread, between the supporting segments (32) and centring disc (33) there are supporting rods (34), and the hinge assembly (35) that maintains concentric spanning are in interlocked moving connection with spanning capstan (37) that moves on external-threaded 20 hub (36).

11) An equipment as claimed in any of previous claims, characterized in that back-up of tire sidewall during its milling is maintained by a supporting die (132) that corresponds to the counter-shape of the opposite side of the sidewall, and centring of work-

25 piece is maintained by upright wing-pieces (133, 137) that fit to the actual position of bead rim of the sidewall, and the on-site fastening of the sidewall in the milling area is made by a pneumatic-driven roll-type hold-down unit (134). 12) An equipment as claimed in any of previous claims, characterized in that the milling of internal rubber layer of tread-band of tire (31) is performed by belt-type milling equipment, where supporting of workpiece is made by plane plate-surfaces (202, 203) and for its forwarding synchronized roll-pairs (207, 208 and 209, 210) are arranged, and for its supporting at the milling place there is a fixed spacer (206) arranged between a pair of supporting rolls (204, 205).

13) An equipment as claimed in claim 11, characterized in that transfer of feeding force at driving rolls (207, 208 and 209, 210) is controlled by pushing force perpendicu- lar to the surface of workpiece, and the surface of pull-side rolls (209, 210) is covered with a material of increased friction property.

14) An equipment as claimed in any of previous claims, characterized in that for the sake of operation-safe feeding of ultra-high pressure liquid to the high-speed vibrating milling head (40, 140, 240) the applied flexible hoses (46) are arranged along a compensation curve, and the connections of the hose are made with anti-vibration connectors that allow a minimum +/-1° but not more than +/- 2,5° inclination of the feeding hose.

15) An equipment as claimed in any of previous claims, characterized in that the homogenous grain dispergation in product-collecting and slurry tank (60) is maintained by a slurry mixer driven from outside of tank.

16) An equipment as claimed in any of previous claims, characterized in that for the promotion of slurry discharging from collecting tank (60) the bottom of tank (61) has a product sedimentation preventing inclination of 3-5°, and magnetic separators are also applied with bottom settling spaces between spillways.

17) An equipment as claimed in any of previous claims, characterized in that top and side covers (11) of milling compartment including the doors (12, 13) of equipment have inclined shaping for the promotion of gravitation drainage of the liquid splashing to internal machine walls and of condensing steam phase produced during milling process.

18) An equipment as claimed in any of previous claims, characterized in that doors (12, 13) of the equipment have vapour-tight sealing, which sealing also provides vibration-damping and noise-insulating function.

19) An equipment as claimed in any of previous claims, characterized in that mechanical components that would pollute the product or the milling liquid may not be ap- plied inside the milling compartment (e.g. hydraulic cylinder), and the rotating or moving components, driving shafts shall be led into milling section via multiple labyrinth- packing.